title: Drought variability in the Pacific Northwest from a 6,000-yr lake sediment record.
abstract: We present a 6,000-yr record of changing water balance in the Pacific Northwest inferred from measurements of carbonate δ(18)O and grayscale on a sediment core collected from Castor Lake, Washington. This subdecadally resolved drought record tracks the 1,500-yr tree-ring-based Palmer Drought Severity Index reconstructions of Cook et al. [Cook ER, Woodhouse CA, Eakin CM, Meko DM, Stahle DW (2004) Science 306:1015-1018] in the Pacific Northwest and extends our knowledge back to 6,000 yr B.P. The results demonstrate that low-frequency drought/pluvial cycles, with occasional long-duration, multidecadal events, are a persistent feature of regional climate. Furthermore, the average duration of multidecadal wet/dry cycles has increased since the middle Holocene, which has acted to increase the amplitude and impact of these events. This is especially apparent during the last 1,000 yr. We suggest these transitions were driven by changes in the tropical and extratropical Pacific and are related to apparent intensification of the El Niño Southern Oscillation over this interval and its related effects on the Pacific Decadal Oscillation. The Castor Lake record also corroborates the notion that the 20th century, prior to recent aridity, was a relatively wet period compared to the last 6,000 yr. Our findings suggest that the hydroclimate response in the Pacific Northwest to future warming will be intimately tied to the impact of warming on the El Niño Southern Oscillation.
authors.affiliation: Geology and Planetary Science, University of Pittsburgh, 4107 O'Hara Street, Room 200, Space Research Coordination Center, Pittsburgh, PA 15260, USA.
authors.forename: Daniel B
authors.initials: DB
authors.lastname: Nelson
authors.forename: Mark B
authors.initials: MB
authors.lastname: Abbott
authors.forename: Byron
authors.initials: B
authors.lastname: Steinman
authors.forename: Pratigya J
authors.initials: PJ
authors.lastname: Polissar
authors.forename: Nathan D
authors.initials: ND
authors.lastname: Stansell
authors.forename: Joseph D
authors.initials: JD
authors.lastname: Ortiz
authors.forename: Michael F
authors.initials: MF
authors.lastname: Rosenmeier
authors.forename: Bruce P
authors.initials: BP
authors.lastname: Finney
authors.forename: Jon
authors.initials: J
authors.lastname: Riedel
mesh_terms: D055864:Droughts; D005618:Fresh Water; D019015:Geologic Sediments; D015205:Northwestern United States